Lead Phosphite, PbHPO3

Lead Phosphite, PbHPO3, is a white powder obtained by precipitating a lead salt solution by a soluble phosphite, or by neutralising phosphorous acid with lead carbonate. When heated it is converted into phosphine and phosphate. Its heat of formation from its elements is 227,700 calories. The acid salt Pb(H2PO3)2 is obtained by dissolving PbHPO3 in phosphorous acid, and by ignition in a vacuum yields the pyrophosphite PbH2P2O5. A basic phosphite exists which is 3PbO.P2O3.2H2O or 4PbO.P2O3.2H2O.